[Bug rtl-optimization/48141] New: [4.4/4.5/4.6/4.7 Regression] DSE compile time hog

["jakub at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48141

           Summary: [4.4/4.5/4.6/4.7 Regression] DSE compile time hog
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Keywords: compile-time-hog
          Severity: normal
          Priority: P3
         Component: rtl-optimization
        AssignedTo: jakub@gcc.gnu.org
        ReportedBy: jakub@gcc.gnu.org


#define A i = 0;
#define B A A A A A A A A A A
#define C B B B B B B B B B B
#define D C C C C C C C C C C
#define E D D D D D D D D D D

int
foo (void)
{
  volatile int i = 0;
  E E E E E E E E E E E
  return 0;
}

compiles at -O in under 4 seconds in 4.3, but in 4.4+ takes almost 8 minutes,
99% of the time spent in RTL DSE, and as it is quadratic, trying 10 times as
many stores makes things much worse.